Loading...
Note: File does not exist in v3.1.
1/*
2 * Helpers for the host side of a virtio ring.
3 *
4 * Since these may be in userspace, we use (inline) accessors.
5 */
6#include <linux/compiler.h>
7#include <linux/module.h>
8#include <linux/vringh.h>
9#include <linux/virtio_ring.h>
10#include <linux/kernel.h>
11#include <linux/ratelimit.h>
12#include <linux/uaccess.h>
13#include <linux/slab.h>
14#include <linux/export.h>
15#include <uapi/linux/virtio_config.h>
16
17static __printf(1,2) __cold void vringh_bad(const char *fmt, ...)
18{
19 static DEFINE_RATELIMIT_STATE(vringh_rs,
20 DEFAULT_RATELIMIT_INTERVAL,
21 DEFAULT_RATELIMIT_BURST);
22 if (__ratelimit(&vringh_rs)) {
23 va_list ap;
24 va_start(ap, fmt);
25 printk(KERN_NOTICE "vringh:");
26 vprintk(fmt, ap);
27 va_end(ap);
28 }
29}
30
31/* Returns vring->num if empty, -ve on error. */
32static inline int __vringh_get_head(const struct vringh *vrh,
33 int (*getu16)(const struct vringh *vrh,
34 u16 *val, const __virtio16 *p),
35 u16 *last_avail_idx)
36{
37 u16 avail_idx, i, head;
38 int err;
39
40 err = getu16(vrh, &avail_idx, &vrh->vring.avail->idx);
41 if (err) {
42 vringh_bad("Failed to access avail idx at %p",
43 &vrh->vring.avail->idx);
44 return err;
45 }
46
47 if (*last_avail_idx == avail_idx)
48 return vrh->vring.num;
49
50 /* Only get avail ring entries after they have been exposed by guest. */
51 virtio_rmb(vrh->weak_barriers);
52
53 i = *last_avail_idx & (vrh->vring.num - 1);
54
55 err = getu16(vrh, &head, &vrh->vring.avail->ring[i]);
56 if (err) {
57 vringh_bad("Failed to read head: idx %d address %p",
58 *last_avail_idx, &vrh->vring.avail->ring[i]);
59 return err;
60 }
61
62 if (head >= vrh->vring.num) {
63 vringh_bad("Guest says index %u > %u is available",
64 head, vrh->vring.num);
65 return -EINVAL;
66 }
67
68 (*last_avail_idx)++;
69 return head;
70}
71
72/* Copy some bytes to/from the iovec. Returns num copied. */
73static inline ssize_t vringh_iov_xfer(struct vringh_kiov *iov,
74 void *ptr, size_t len,
75 int (*xfer)(void *addr, void *ptr,
76 size_t len))
77{
78 int err, done = 0;
79
80 while (len && iov->i < iov->used) {
81 size_t partlen;
82
83 partlen = min(iov->iov[iov->i].iov_len, len);
84 err = xfer(iov->iov[iov->i].iov_base, ptr, partlen);
85 if (err)
86 return err;
87 done += partlen;
88 len -= partlen;
89 ptr += partlen;
90 iov->consumed += partlen;
91 iov->iov[iov->i].iov_len -= partlen;
92 iov->iov[iov->i].iov_base += partlen;
93
94 if (!iov->iov[iov->i].iov_len) {
95 /* Fix up old iov element then increment. */
96 iov->iov[iov->i].iov_len = iov->consumed;
97 iov->iov[iov->i].iov_base -= iov->consumed;
98
99 iov->consumed = 0;
100 iov->i++;
101 }
102 }
103 return done;
104}
105
106/* May reduce *len if range is shorter. */
107static inline bool range_check(struct vringh *vrh, u64 addr, size_t *len,
108 struct vringh_range *range,
109 bool (*getrange)(struct vringh *,
110 u64, struct vringh_range *))
111{
112 if (addr < range->start || addr > range->end_incl) {
113 if (!getrange(vrh, addr, range))
114 return false;
115 }
116 BUG_ON(addr < range->start || addr > range->end_incl);
117
118 /* To end of memory? */
119 if (unlikely(addr + *len == 0)) {
120 if (range->end_incl == -1ULL)
121 return true;
122 goto truncate;
123 }
124
125 /* Otherwise, don't wrap. */
126 if (addr + *len < addr) {
127 vringh_bad("Wrapping descriptor %zu@0x%llx",
128 *len, (unsigned long long)addr);
129 return false;
130 }
131
132 if (unlikely(addr + *len - 1 > range->end_incl))
133 goto truncate;
134 return true;
135
136truncate:
137 *len = range->end_incl + 1 - addr;
138 return true;
139}
140
141static inline bool no_range_check(struct vringh *vrh, u64 addr, size_t *len,
142 struct vringh_range *range,
143 bool (*getrange)(struct vringh *,
144 u64, struct vringh_range *))
145{
146 return true;
147}
148
149/* No reason for this code to be inline. */
150static int move_to_indirect(const struct vringh *vrh,
151 int *up_next, u16 *i, void *addr,
152 const struct vring_desc *desc,
153 struct vring_desc **descs, int *desc_max)
154{
155 u32 len;
156
157 /* Indirect tables can't have indirect. */
158 if (*up_next != -1) {
159 vringh_bad("Multilevel indirect %u->%u", *up_next, *i);
160 return -EINVAL;
161 }
162
163 len = vringh32_to_cpu(vrh, desc->len);
164 if (unlikely(len % sizeof(struct vring_desc))) {
165 vringh_bad("Strange indirect len %u", desc->len);
166 return -EINVAL;
167 }
168
169 /* We will check this when we follow it! */
170 if (desc->flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT))
171 *up_next = vringh16_to_cpu(vrh, desc->next);
172 else
173 *up_next = -2;
174 *descs = addr;
175 *desc_max = len / sizeof(struct vring_desc);
176
177 /* Now, start at the first indirect. */
178 *i = 0;
179 return 0;
180}
181
182static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp)
183{
184 struct kvec *new;
185 unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2;
186
187 if (new_num < 8)
188 new_num = 8;
189
190 flag = (iov->max_num & VRINGH_IOV_ALLOCATED);
191 if (flag)
192 new = krealloc(iov->iov, new_num * sizeof(struct iovec), gfp);
193 else {
194 new = kmalloc(new_num * sizeof(struct iovec), gfp);
195 if (new) {
196 memcpy(new, iov->iov,
197 iov->max_num * sizeof(struct iovec));
198 flag = VRINGH_IOV_ALLOCATED;
199 }
200 }
201 if (!new)
202 return -ENOMEM;
203 iov->iov = new;
204 iov->max_num = (new_num | flag);
205 return 0;
206}
207
208static u16 __cold return_from_indirect(const struct vringh *vrh, int *up_next,
209 struct vring_desc **descs, int *desc_max)
210{
211 u16 i = *up_next;
212
213 *up_next = -1;
214 *descs = vrh->vring.desc;
215 *desc_max = vrh->vring.num;
216 return i;
217}
218
219static int slow_copy(struct vringh *vrh, void *dst, const void *src,
220 bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
221 struct vringh_range *range,
222 bool (*getrange)(struct vringh *vrh,
223 u64,
224 struct vringh_range *)),
225 bool (*getrange)(struct vringh *vrh,
226 u64 addr,
227 struct vringh_range *r),
228 struct vringh_range *range,
229 int (*copy)(void *dst, const void *src, size_t len))
230{
231 size_t part, len = sizeof(struct vring_desc);
232
233 do {
234 u64 addr;
235 int err;
236
237 part = len;
238 addr = (u64)(unsigned long)src - range->offset;
239
240 if (!rcheck(vrh, addr, &part, range, getrange))
241 return -EINVAL;
242
243 err = copy(dst, src, part);
244 if (err)
245 return err;
246
247 dst += part;
248 src += part;
249 len -= part;
250 } while (len);
251 return 0;
252}
253
254static inline int
255__vringh_iov(struct vringh *vrh, u16 i,
256 struct vringh_kiov *riov,
257 struct vringh_kiov *wiov,
258 bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
259 struct vringh_range *range,
260 bool (*getrange)(struct vringh *, u64,
261 struct vringh_range *)),
262 bool (*getrange)(struct vringh *, u64, struct vringh_range *),
263 gfp_t gfp,
264 int (*copy)(void *dst, const void *src, size_t len))
265{
266 int err, count = 0, up_next, desc_max;
267 struct vring_desc desc, *descs;
268 struct vringh_range range = { -1ULL, 0 }, slowrange;
269 bool slow = false;
270
271 /* We start traversing vring's descriptor table. */
272 descs = vrh->vring.desc;
273 desc_max = vrh->vring.num;
274 up_next = -1;
275
276 if (riov)
277 riov->i = riov->used = 0;
278 else if (wiov)
279 wiov->i = wiov->used = 0;
280 else
281 /* You must want something! */
282 BUG();
283
284 for (;;) {
285 void *addr;
286 struct vringh_kiov *iov;
287 size_t len;
288
289 if (unlikely(slow))
290 err = slow_copy(vrh, &desc, &descs[i], rcheck, getrange,
291 &slowrange, copy);
292 else
293 err = copy(&desc, &descs[i], sizeof(desc));
294 if (unlikely(err))
295 goto fail;
296
297 if (unlikely(desc.flags &
298 cpu_to_vringh16(vrh, VRING_DESC_F_INDIRECT))) {
299 u64 a = vringh64_to_cpu(vrh, desc.addr);
300
301 /* Make sure it's OK, and get offset. */
302 len = vringh32_to_cpu(vrh, desc.len);
303 if (!rcheck(vrh, a, &len, &range, getrange)) {
304 err = -EINVAL;
305 goto fail;
306 }
307
308 if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) {
309 slow = true;
310 /* We need to save this range to use offset */
311 slowrange = range;
312 }
313
314 addr = (void *)(long)(a + range.offset);
315 err = move_to_indirect(vrh, &up_next, &i, addr, &desc,
316 &descs, &desc_max);
317 if (err)
318 goto fail;
319 continue;
320 }
321
322 if (count++ == vrh->vring.num) {
323 vringh_bad("Descriptor loop in %p", descs);
324 err = -ELOOP;
325 goto fail;
326 }
327
328 if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_WRITE))
329 iov = wiov;
330 else {
331 iov = riov;
332 if (unlikely(wiov && wiov->i)) {
333 vringh_bad("Readable desc %p after writable",
334 &descs[i]);
335 err = -EINVAL;
336 goto fail;
337 }
338 }
339
340 if (!iov) {
341 vringh_bad("Unexpected %s desc",
342 !wiov ? "writable" : "readable");
343 err = -EPROTO;
344 goto fail;
345 }
346
347 again:
348 /* Make sure it's OK, and get offset. */
349 len = vringh32_to_cpu(vrh, desc.len);
350 if (!rcheck(vrh, vringh64_to_cpu(vrh, desc.addr), &len, &range,
351 getrange)) {
352 err = -EINVAL;
353 goto fail;
354 }
355 addr = (void *)(unsigned long)(vringh64_to_cpu(vrh, desc.addr) +
356 range.offset);
357
358 if (unlikely(iov->used == (iov->max_num & ~VRINGH_IOV_ALLOCATED))) {
359 err = resize_iovec(iov, gfp);
360 if (err)
361 goto fail;
362 }
363
364 iov->iov[iov->used].iov_base = addr;
365 iov->iov[iov->used].iov_len = len;
366 iov->used++;
367
368 if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) {
369 desc.len = cpu_to_vringh32(vrh,
370 vringh32_to_cpu(vrh, desc.len) - len);
371 desc.addr = cpu_to_vringh64(vrh,
372 vringh64_to_cpu(vrh, desc.addr) + len);
373 goto again;
374 }
375
376 if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT)) {
377 i = vringh16_to_cpu(vrh, desc.next);
378 } else {
379 /* Just in case we need to finish traversing above. */
380 if (unlikely(up_next > 0)) {
381 i = return_from_indirect(vrh, &up_next,
382 &descs, &desc_max);
383 slow = false;
384 } else
385 break;
386 }
387
388 if (i >= desc_max) {
389 vringh_bad("Chained index %u > %u", i, desc_max);
390 err = -EINVAL;
391 goto fail;
392 }
393 }
394
395 return 0;
396
397fail:
398 return err;
399}
400
401static inline int __vringh_complete(struct vringh *vrh,
402 const struct vring_used_elem *used,
403 unsigned int num_used,
404 int (*putu16)(const struct vringh *vrh,
405 __virtio16 *p, u16 val),
406 int (*putused)(struct vring_used_elem *dst,
407 const struct vring_used_elem
408 *src, unsigned num))
409{
410 struct vring_used *used_ring;
411 int err;
412 u16 used_idx, off;
413
414 used_ring = vrh->vring.used;
415 used_idx = vrh->last_used_idx + vrh->completed;
416
417 off = used_idx % vrh->vring.num;
418
419 /* Compiler knows num_used == 1 sometimes, hence extra check */
420 if (num_used > 1 && unlikely(off + num_used >= vrh->vring.num)) {
421 u16 part = vrh->vring.num - off;
422 err = putused(&used_ring->ring[off], used, part);
423 if (!err)
424 err = putused(&used_ring->ring[0], used + part,
425 num_used - part);
426 } else
427 err = putused(&used_ring->ring[off], used, num_used);
428
429 if (err) {
430 vringh_bad("Failed to write %u used entries %u at %p",
431 num_used, off, &used_ring->ring[off]);
432 return err;
433 }
434
435 /* Make sure buffer is written before we update index. */
436 virtio_wmb(vrh->weak_barriers);
437
438 err = putu16(vrh, &vrh->vring.used->idx, used_idx + num_used);
439 if (err) {
440 vringh_bad("Failed to update used index at %p",
441 &vrh->vring.used->idx);
442 return err;
443 }
444
445 vrh->completed += num_used;
446 return 0;
447}
448
449
450static inline int __vringh_need_notify(struct vringh *vrh,
451 int (*getu16)(const struct vringh *vrh,
452 u16 *val,
453 const __virtio16 *p))
454{
455 bool notify;
456 u16 used_event;
457 int err;
458
459 /* Flush out used index update. This is paired with the
460 * barrier that the Guest executes when enabling
461 * interrupts. */
462 virtio_mb(vrh->weak_barriers);
463
464 /* Old-style, without event indices. */
465 if (!vrh->event_indices) {
466 u16 flags;
467 err = getu16(vrh, &flags, &vrh->vring.avail->flags);
468 if (err) {
469 vringh_bad("Failed to get flags at %p",
470 &vrh->vring.avail->flags);
471 return err;
472 }
473 return (!(flags & VRING_AVAIL_F_NO_INTERRUPT));
474 }
475
476 /* Modern: we know when other side wants to know. */
477 err = getu16(vrh, &used_event, &vring_used_event(&vrh->vring));
478 if (err) {
479 vringh_bad("Failed to get used event idx at %p",
480 &vring_used_event(&vrh->vring));
481 return err;
482 }
483
484 /* Just in case we added so many that we wrap. */
485 if (unlikely(vrh->completed > 0xffff))
486 notify = true;
487 else
488 notify = vring_need_event(used_event,
489 vrh->last_used_idx + vrh->completed,
490 vrh->last_used_idx);
491
492 vrh->last_used_idx += vrh->completed;
493 vrh->completed = 0;
494 return notify;
495}
496
497static inline bool __vringh_notify_enable(struct vringh *vrh,
498 int (*getu16)(const struct vringh *vrh,
499 u16 *val, const __virtio16 *p),
500 int (*putu16)(const struct vringh *vrh,
501 __virtio16 *p, u16 val))
502{
503 u16 avail;
504
505 if (!vrh->event_indices) {
506 /* Old-school; update flags. */
507 if (putu16(vrh, &vrh->vring.used->flags, 0) != 0) {
508 vringh_bad("Clearing used flags %p",
509 &vrh->vring.used->flags);
510 return true;
511 }
512 } else {
513 if (putu16(vrh, &vring_avail_event(&vrh->vring),
514 vrh->last_avail_idx) != 0) {
515 vringh_bad("Updating avail event index %p",
516 &vring_avail_event(&vrh->vring));
517 return true;
518 }
519 }
520
521 /* They could have slipped one in as we were doing that: make
522 * sure it's written, then check again. */
523 virtio_mb(vrh->weak_barriers);
524
525 if (getu16(vrh, &avail, &vrh->vring.avail->idx) != 0) {
526 vringh_bad("Failed to check avail idx at %p",
527 &vrh->vring.avail->idx);
528 return true;
529 }
530
531 /* This is unlikely, so we just leave notifications enabled
532 * (if we're using event_indices, we'll only get one
533 * notification anyway). */
534 return avail == vrh->last_avail_idx;
535}
536
537static inline void __vringh_notify_disable(struct vringh *vrh,
538 int (*putu16)(const struct vringh *vrh,
539 __virtio16 *p, u16 val))
540{
541 if (!vrh->event_indices) {
542 /* Old-school; update flags. */
543 if (putu16(vrh, &vrh->vring.used->flags,
544 VRING_USED_F_NO_NOTIFY)) {
545 vringh_bad("Setting used flags %p",
546 &vrh->vring.used->flags);
547 }
548 }
549}
550
551/* Userspace access helpers: in this case, addresses are really userspace. */
552static inline int getu16_user(const struct vringh *vrh, u16 *val, const __virtio16 *p)
553{
554 __virtio16 v = 0;
555 int rc = get_user(v, (__force __virtio16 __user *)p);
556 *val = vringh16_to_cpu(vrh, v);
557 return rc;
558}
559
560static inline int putu16_user(const struct vringh *vrh, __virtio16 *p, u16 val)
561{
562 __virtio16 v = cpu_to_vringh16(vrh, val);
563 return put_user(v, (__force __virtio16 __user *)p);
564}
565
566static inline int copydesc_user(void *dst, const void *src, size_t len)
567{
568 return copy_from_user(dst, (__force void __user *)src, len) ?
569 -EFAULT : 0;
570}
571
572static inline int putused_user(struct vring_used_elem *dst,
573 const struct vring_used_elem *src,
574 unsigned int num)
575{
576 return copy_to_user((__force void __user *)dst, src,
577 sizeof(*dst) * num) ? -EFAULT : 0;
578}
579
580static inline int xfer_from_user(void *src, void *dst, size_t len)
581{
582 return copy_from_user(dst, (__force void __user *)src, len) ?
583 -EFAULT : 0;
584}
585
586static inline int xfer_to_user(void *dst, void *src, size_t len)
587{
588 return copy_to_user((__force void __user *)dst, src, len) ?
589 -EFAULT : 0;
590}
591
592/**
593 * vringh_init_user - initialize a vringh for a userspace vring.
594 * @vrh: the vringh to initialize.
595 * @features: the feature bits for this ring.
596 * @num: the number of elements.
597 * @weak_barriers: true if we only need memory barriers, not I/O.
598 * @desc: the userpace descriptor pointer.
599 * @avail: the userpace avail pointer.
600 * @used: the userpace used pointer.
601 *
602 * Returns an error if num is invalid: you should check pointers
603 * yourself!
604 */
605int vringh_init_user(struct vringh *vrh, u64 features,
606 unsigned int num, bool weak_barriers,
607 struct vring_desc __user *desc,
608 struct vring_avail __user *avail,
609 struct vring_used __user *used)
610{
611 /* Sane power of 2 please! */
612 if (!num || num > 0xffff || (num & (num - 1))) {
613 vringh_bad("Bad ring size %u", num);
614 return -EINVAL;
615 }
616
617 vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
618 vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
619 vrh->weak_barriers = weak_barriers;
620 vrh->completed = 0;
621 vrh->last_avail_idx = 0;
622 vrh->last_used_idx = 0;
623 vrh->vring.num = num;
624 /* vring expects kernel addresses, but only used via accessors. */
625 vrh->vring.desc = (__force struct vring_desc *)desc;
626 vrh->vring.avail = (__force struct vring_avail *)avail;
627 vrh->vring.used = (__force struct vring_used *)used;
628 return 0;
629}
630EXPORT_SYMBOL(vringh_init_user);
631
632/**
633 * vringh_getdesc_user - get next available descriptor from userspace ring.
634 * @vrh: the userspace vring.
635 * @riov: where to put the readable descriptors (or NULL)
636 * @wiov: where to put the writable descriptors (or NULL)
637 * @getrange: function to call to check ranges.
638 * @head: head index we received, for passing to vringh_complete_user().
639 *
640 * Returns 0 if there was no descriptor, 1 if there was, or -errno.
641 *
642 * Note that on error return, you can tell the difference between an
643 * invalid ring and a single invalid descriptor: in the former case,
644 * *head will be vrh->vring.num. You may be able to ignore an invalid
645 * descriptor, but there's not much you can do with an invalid ring.
646 *
647 * Note that you may need to clean up riov and wiov, even on error!
648 */
649int vringh_getdesc_user(struct vringh *vrh,
650 struct vringh_iov *riov,
651 struct vringh_iov *wiov,
652 bool (*getrange)(struct vringh *vrh,
653 u64 addr, struct vringh_range *r),
654 u16 *head)
655{
656 int err;
657
658 *head = vrh->vring.num;
659 err = __vringh_get_head(vrh, getu16_user, &vrh->last_avail_idx);
660 if (err < 0)
661 return err;
662
663 /* Empty... */
664 if (err == vrh->vring.num)
665 return 0;
666
667 /* We need the layouts to be the identical for this to work */
668 BUILD_BUG_ON(sizeof(struct vringh_kiov) != sizeof(struct vringh_iov));
669 BUILD_BUG_ON(offsetof(struct vringh_kiov, iov) !=
670 offsetof(struct vringh_iov, iov));
671 BUILD_BUG_ON(offsetof(struct vringh_kiov, i) !=
672 offsetof(struct vringh_iov, i));
673 BUILD_BUG_ON(offsetof(struct vringh_kiov, used) !=
674 offsetof(struct vringh_iov, used));
675 BUILD_BUG_ON(offsetof(struct vringh_kiov, max_num) !=
676 offsetof(struct vringh_iov, max_num));
677 BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec));
678 BUILD_BUG_ON(offsetof(struct iovec, iov_base) !=
679 offsetof(struct kvec, iov_base));
680 BUILD_BUG_ON(offsetof(struct iovec, iov_len) !=
681 offsetof(struct kvec, iov_len));
682 BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_base)
683 != sizeof(((struct kvec *)NULL)->iov_base));
684 BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_len)
685 != sizeof(((struct kvec *)NULL)->iov_len));
686
687 *head = err;
688 err = __vringh_iov(vrh, *head, (struct vringh_kiov *)riov,
689 (struct vringh_kiov *)wiov,
690 range_check, getrange, GFP_KERNEL, copydesc_user);
691 if (err)
692 return err;
693
694 return 1;
695}
696EXPORT_SYMBOL(vringh_getdesc_user);
697
698/**
699 * vringh_iov_pull_user - copy bytes from vring_iov.
700 * @riov: the riov as passed to vringh_getdesc_user() (updated as we consume)
701 * @dst: the place to copy.
702 * @len: the maximum length to copy.
703 *
704 * Returns the bytes copied <= len or a negative errno.
705 */
706ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len)
707{
708 return vringh_iov_xfer((struct vringh_kiov *)riov,
709 dst, len, xfer_from_user);
710}
711EXPORT_SYMBOL(vringh_iov_pull_user);
712
713/**
714 * vringh_iov_push_user - copy bytes into vring_iov.
715 * @wiov: the wiov as passed to vringh_getdesc_user() (updated as we consume)
716 * @dst: the place to copy.
717 * @len: the maximum length to copy.
718 *
719 * Returns the bytes copied <= len or a negative errno.
720 */
721ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
722 const void *src, size_t len)
723{
724 return vringh_iov_xfer((struct vringh_kiov *)wiov,
725 (void *)src, len, xfer_to_user);
726}
727EXPORT_SYMBOL(vringh_iov_push_user);
728
729/**
730 * vringh_abandon_user - we've decided not to handle the descriptor(s).
731 * @vrh: the vring.
732 * @num: the number of descriptors to put back (ie. num
733 * vringh_get_user() to undo).
734 *
735 * The next vringh_get_user() will return the old descriptor(s) again.
736 */
737void vringh_abandon_user(struct vringh *vrh, unsigned int num)
738{
739 /* We only update vring_avail_event(vr) when we want to be notified,
740 * so we haven't changed that yet. */
741 vrh->last_avail_idx -= num;
742}
743EXPORT_SYMBOL(vringh_abandon_user);
744
745/**
746 * vringh_complete_user - we've finished with descriptor, publish it.
747 * @vrh: the vring.
748 * @head: the head as filled in by vringh_getdesc_user.
749 * @len: the length of data we have written.
750 *
751 * You should check vringh_need_notify_user() after one or more calls
752 * to this function.
753 */
754int vringh_complete_user(struct vringh *vrh, u16 head, u32 len)
755{
756 struct vring_used_elem used;
757
758 used.id = cpu_to_vringh32(vrh, head);
759 used.len = cpu_to_vringh32(vrh, len);
760 return __vringh_complete(vrh, &used, 1, putu16_user, putused_user);
761}
762EXPORT_SYMBOL(vringh_complete_user);
763
764/**
765 * vringh_complete_multi_user - we've finished with many descriptors.
766 * @vrh: the vring.
767 * @used: the head, length pairs.
768 * @num_used: the number of used elements.
769 *
770 * You should check vringh_need_notify_user() after one or more calls
771 * to this function.
772 */
773int vringh_complete_multi_user(struct vringh *vrh,
774 const struct vring_used_elem used[],
775 unsigned num_used)
776{
777 return __vringh_complete(vrh, used, num_used,
778 putu16_user, putused_user);
779}
780EXPORT_SYMBOL(vringh_complete_multi_user);
781
782/**
783 * vringh_notify_enable_user - we want to know if something changes.
784 * @vrh: the vring.
785 *
786 * This always enables notifications, but returns false if there are
787 * now more buffers available in the vring.
788 */
789bool vringh_notify_enable_user(struct vringh *vrh)
790{
791 return __vringh_notify_enable(vrh, getu16_user, putu16_user);
792}
793EXPORT_SYMBOL(vringh_notify_enable_user);
794
795/**
796 * vringh_notify_disable_user - don't tell us if something changes.
797 * @vrh: the vring.
798 *
799 * This is our normal running state: we disable and then only enable when
800 * we're going to sleep.
801 */
802void vringh_notify_disable_user(struct vringh *vrh)
803{
804 __vringh_notify_disable(vrh, putu16_user);
805}
806EXPORT_SYMBOL(vringh_notify_disable_user);
807
808/**
809 * vringh_need_notify_user - must we tell the other side about used buffers?
810 * @vrh: the vring we've called vringh_complete_user() on.
811 *
812 * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
813 */
814int vringh_need_notify_user(struct vringh *vrh)
815{
816 return __vringh_need_notify(vrh, getu16_user);
817}
818EXPORT_SYMBOL(vringh_need_notify_user);
819
820/* Kernelspace access helpers. */
821static inline int getu16_kern(const struct vringh *vrh,
822 u16 *val, const __virtio16 *p)
823{
824 *val = vringh16_to_cpu(vrh, READ_ONCE(*p));
825 return 0;
826}
827
828static inline int putu16_kern(const struct vringh *vrh, __virtio16 *p, u16 val)
829{
830 WRITE_ONCE(*p, cpu_to_vringh16(vrh, val));
831 return 0;
832}
833
834static inline int copydesc_kern(void *dst, const void *src, size_t len)
835{
836 memcpy(dst, src, len);
837 return 0;
838}
839
840static inline int putused_kern(struct vring_used_elem *dst,
841 const struct vring_used_elem *src,
842 unsigned int num)
843{
844 memcpy(dst, src, num * sizeof(*dst));
845 return 0;
846}
847
848static inline int xfer_kern(void *src, void *dst, size_t len)
849{
850 memcpy(dst, src, len);
851 return 0;
852}
853
854/**
855 * vringh_init_kern - initialize a vringh for a kernelspace vring.
856 * @vrh: the vringh to initialize.
857 * @features: the feature bits for this ring.
858 * @num: the number of elements.
859 * @weak_barriers: true if we only need memory barriers, not I/O.
860 * @desc: the userpace descriptor pointer.
861 * @avail: the userpace avail pointer.
862 * @used: the userpace used pointer.
863 *
864 * Returns an error if num is invalid.
865 */
866int vringh_init_kern(struct vringh *vrh, u64 features,
867 unsigned int num, bool weak_barriers,
868 struct vring_desc *desc,
869 struct vring_avail *avail,
870 struct vring_used *used)
871{
872 /* Sane power of 2 please! */
873 if (!num || num > 0xffff || (num & (num - 1))) {
874 vringh_bad("Bad ring size %u", num);
875 return -EINVAL;
876 }
877
878 vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
879 vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
880 vrh->weak_barriers = weak_barriers;
881 vrh->completed = 0;
882 vrh->last_avail_idx = 0;
883 vrh->last_used_idx = 0;
884 vrh->vring.num = num;
885 vrh->vring.desc = desc;
886 vrh->vring.avail = avail;
887 vrh->vring.used = used;
888 return 0;
889}
890EXPORT_SYMBOL(vringh_init_kern);
891
892/**
893 * vringh_getdesc_kern - get next available descriptor from kernelspace ring.
894 * @vrh: the kernelspace vring.
895 * @riov: where to put the readable descriptors (or NULL)
896 * @wiov: where to put the writable descriptors (or NULL)
897 * @head: head index we received, for passing to vringh_complete_kern().
898 * @gfp: flags for allocating larger riov/wiov.
899 *
900 * Returns 0 if there was no descriptor, 1 if there was, or -errno.
901 *
902 * Note that on error return, you can tell the difference between an
903 * invalid ring and a single invalid descriptor: in the former case,
904 * *head will be vrh->vring.num. You may be able to ignore an invalid
905 * descriptor, but there's not much you can do with an invalid ring.
906 *
907 * Note that you may need to clean up riov and wiov, even on error!
908 */
909int vringh_getdesc_kern(struct vringh *vrh,
910 struct vringh_kiov *riov,
911 struct vringh_kiov *wiov,
912 u16 *head,
913 gfp_t gfp)
914{
915 int err;
916
917 err = __vringh_get_head(vrh, getu16_kern, &vrh->last_avail_idx);
918 if (err < 0)
919 return err;
920
921 /* Empty... */
922 if (err == vrh->vring.num)
923 return 0;
924
925 *head = err;
926 err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL,
927 gfp, copydesc_kern);
928 if (err)
929 return err;
930
931 return 1;
932}
933EXPORT_SYMBOL(vringh_getdesc_kern);
934
935/**
936 * vringh_iov_pull_kern - copy bytes from vring_iov.
937 * @riov: the riov as passed to vringh_getdesc_kern() (updated as we consume)
938 * @dst: the place to copy.
939 * @len: the maximum length to copy.
940 *
941 * Returns the bytes copied <= len or a negative errno.
942 */
943ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len)
944{
945 return vringh_iov_xfer(riov, dst, len, xfer_kern);
946}
947EXPORT_SYMBOL(vringh_iov_pull_kern);
948
949/**
950 * vringh_iov_push_kern - copy bytes into vring_iov.
951 * @wiov: the wiov as passed to vringh_getdesc_kern() (updated as we consume)
952 * @dst: the place to copy.
953 * @len: the maximum length to copy.
954 *
955 * Returns the bytes copied <= len or a negative errno.
956 */
957ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
958 const void *src, size_t len)
959{
960 return vringh_iov_xfer(wiov, (void *)src, len, xfer_kern);
961}
962EXPORT_SYMBOL(vringh_iov_push_kern);
963
964/**
965 * vringh_abandon_kern - we've decided not to handle the descriptor(s).
966 * @vrh: the vring.
967 * @num: the number of descriptors to put back (ie. num
968 * vringh_get_kern() to undo).
969 *
970 * The next vringh_get_kern() will return the old descriptor(s) again.
971 */
972void vringh_abandon_kern(struct vringh *vrh, unsigned int num)
973{
974 /* We only update vring_avail_event(vr) when we want to be notified,
975 * so we haven't changed that yet. */
976 vrh->last_avail_idx -= num;
977}
978EXPORT_SYMBOL(vringh_abandon_kern);
979
980/**
981 * vringh_complete_kern - we've finished with descriptor, publish it.
982 * @vrh: the vring.
983 * @head: the head as filled in by vringh_getdesc_kern.
984 * @len: the length of data we have written.
985 *
986 * You should check vringh_need_notify_kern() after one or more calls
987 * to this function.
988 */
989int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len)
990{
991 struct vring_used_elem used;
992
993 used.id = cpu_to_vringh32(vrh, head);
994 used.len = cpu_to_vringh32(vrh, len);
995
996 return __vringh_complete(vrh, &used, 1, putu16_kern, putused_kern);
997}
998EXPORT_SYMBOL(vringh_complete_kern);
999
1000/**
1001 * vringh_notify_enable_kern - we want to know if something changes.
1002 * @vrh: the vring.
1003 *
1004 * This always enables notifications, but returns false if there are
1005 * now more buffers available in the vring.
1006 */
1007bool vringh_notify_enable_kern(struct vringh *vrh)
1008{
1009 return __vringh_notify_enable(vrh, getu16_kern, putu16_kern);
1010}
1011EXPORT_SYMBOL(vringh_notify_enable_kern);
1012
1013/**
1014 * vringh_notify_disable_kern - don't tell us if something changes.
1015 * @vrh: the vring.
1016 *
1017 * This is our normal running state: we disable and then only enable when
1018 * we're going to sleep.
1019 */
1020void vringh_notify_disable_kern(struct vringh *vrh)
1021{
1022 __vringh_notify_disable(vrh, putu16_kern);
1023}
1024EXPORT_SYMBOL(vringh_notify_disable_kern);
1025
1026/**
1027 * vringh_need_notify_kern - must we tell the other side about used buffers?
1028 * @vrh: the vring we've called vringh_complete_kern() on.
1029 *
1030 * Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
1031 */
1032int vringh_need_notify_kern(struct vringh *vrh)
1033{
1034 return __vringh_need_notify(vrh, getu16_kern);
1035}
1036EXPORT_SYMBOL(vringh_need_notify_kern);
1037
1038MODULE_LICENSE("GPL");